Problem: The expression $1.5t + 20$ predicts the height in centimeters of a plant $t$ days from today. What is the predicted height of the plant $5$ days from today?
Predicting the height ${5}$ days from today tells us that $t={5}$. Let's substitute $t={5}$ into the expression and evaluate: $\begin{aligned} &\phantom{=}1.5 + 20\\\\ &= 1.5(5) + 20\\\\ &= 7.5 + 20\\\\ &={27.5} \end{aligned}$ The predicted height of the plant $5$ days from today is ${27.5} \text{ cm}$.